A hybrid vehicle that distributes the driving force which is output by an internal combustion engine (for example, an engine) and the driving force which is output by a rotary electric machine (for example, a motor generator) via a planetary gear mechanism including a sun gear, a carrier, and a ring gear which are capable of differential rotation with respect to one another is known (for example, refer to PTL 1 to PTL 3). In PTL 1, a mechanical oil pump that is driven by using the torque which is output by the internal combustion engine (that is, the rotational torque of a crankshaft connected to the internal combustion engine) is used so as to supply a lubricant to the rotary electric machine.
The hybrid vehicles may travel in an EV traveling mode, in which the hybrid vehicles travel by using the torque that is output by the rotary electric machine in a state where the internal combustion engine is stopped, for the purpose of improving (that is, ameliorating) fuel economy. In a state where the internal combustion engine is stopped, the internal combustion engine outputs no torque (that is, the crankshaft does not rotate), and thus the mechanical oil pump is not driven. In a state where the mechanical oil pump is not driven, a new lubricant is not supplied to the rotary electric machine (that is, lubricant circulation stops), and thus the temperature of the rotary electric machine may increase. PTL 1 proposes a technique for supplying the lubricant to the rotary electric machine by driving the internal combustion engine (that is, stopping the traveling in the EV traveling mode) so as to suppress an increase in the temperature of the rotary electric machine in a case where the temperature of the rotary electric machine is equal to or higher than a predetermined temperature.
In addition, PTL 2 and PTL 3 are two other examples disclosing the technique relating to the invention.
In the hybrid vehicle that is disclosed in PTL 2, the planetary gear mechanism is additionally provided with a clutch which allows or releases the connection between the carrier and an input shaft of the internal combustion engine and a brake which stops the rotation of the carrier. When the clutch is ON (that is, the carrier and the input shaft are engaged with each other) and the brake is ON (that is, the rotation of the carrier is stopped), the hybrid vehicle can travel (for example, perform powering or regeneration) by using the torques of both the rotary electric machine connected to the sun gear and the rotary electric machine connected to the ring gear.
The hybrid vehicle that is disclosed in PTL 3 is additionally provided with a clutch which is capable of allowing or prohibiting torque transmission between the internal combustion engine and the drive shaft. In this hybrid vehicle, the torque transmission between the internal combustion engine and the drive shaft is blocked and a torque for the motoring (that is, rotation) of the internal combustion engine is output from the rotary electric machine in a case where the hybrid vehicle performs regenerative electric power generation. As a result, the torque that is output from the rotary electric machine for the motoring of the internal combustion engine is not transmitted to the drive shaft, and thus a torque change in the drive shaft attributable to the motoring of the internal combustion engine does not occur.